The present invention relates to a semiconductor module, specifically a compact switch module that exhibits good thermal energy dissipation characteristics and is capable of carrying a very large current.
High power applications require that the circuits delivering these currents be capable of carrying very large amounts of current. Certain applications demand current capabilities in excess of 1000 Amperes. A device typically found in such circuits is a switch. For example, the electronic control circuitry for an automotive turbocharger, supercharger, or super-turbocharger requires switching these extremely large currents. Circuit switches are generally available as either mechanical switches or electronic switches. Mechanical switches typically employ a number of metallic contact points which are connected or disconnected by physically moving, either manually or automatically, a conductor between the contact points. Mechanical switches wear out and are prone to breakage.
Electronic switches typically employ transistors, which can be switched on and off by applying a base current or a gate voltage, depending on the type of transistor. Power metal oxide field effect transistors (MOSFETs) and insulated gate bipolar transistors (IGETs) (hereinafter FETs) are used as switching transistors because, among their other useful characteristics, they are easily paralleled and are able to carry large currents. However, because of their resistive characteristics, FET based switches are prone to heating. This becomes problematic when switching high current loads. In addition, high current switching applications employ the use of multiple FETs, whose respective gates, drains and sources are connected in parallel. These parallel configurations require large modules to house the FETs. The modules also require large heatsinks to dissipate the heat, further increasing overall package size.
It is desirable to have a FET based switch module which can reliably switch a large current, is small, exhibits good thermal management properties and can be arranged to have low inductance.